Numbers on the crank are often the same as the part number, but not
always.

Replacement cranks may be a different part number or casting number than
what came in the original engine.

Bearings must be installed in the engine and measured prior to grinding
the crank to get clearances right.

FS = Forged Steel

AS = ARMA STEEL
= PMI Pearlitic Malleable cast iron. ARMA STEEL logo may not be present on all cranks.

ARMA STEEL is not steel, but a form of cast iron. ARMA STEEL was registered trademark #0393916 GM used starting October of 1937. The trademark was last renewed in 1982 and expired in 2002.

N
= Nodular Cast Iron. "N" mark may not be present on all cranks.

CFD
= Central Foundry Division. May not be present on all cranks.

It appears many
cranks do not have a casting date. If they do, it may follow the normal
GM format: A=January, B=February and so on. Second digit or digits is date,
last digit is year. D124 = April 12, 1964 or 1974.

Some
cranks may have a 3 digit number like 205. It may be a Julian
production date, but I have no confirmation of that.

Examples of cast letters
and numbers
The 94054 is an example of stamped numbers